The present invention relates generally to a disconnect switch for high voltage electrical applications and, more particularly, to a folding disconnect switch having a switch blade that folds as it opens and is folded as it begins to close to lower the force necessary to disengage or re-engage the contacts of the switch. One example of such a switch is a folding side break electric disconnect switch such as manufactured and sold by Cleaveland/Price, Inc. of Trafford, Pa., the present assignee, as Model RL-C, a copper side break switch rated at 115 kV, 1200 A. The folding of the switch blade also aids in breaking ice on outdoor disconnect switches as the switch opens or closes. The typical folding blade has two switch blade portions, i.e., a fixed blade portion and a folding blade portion, that are operatively joined by a current carrying joint that is often spring biased to keep the blade in the folded state. The spring at the joint causes the switch blade to fold as it opens which sets up the blade to be in a folded condition prior to re-engaging, for example, reengaging with a notch in the break jaw contact as the switch closes.
In electric utility power systems, high voltage disconnect switches are employed to isolate substation conductors and transmission lines and high voltage electrical apparatus to permit the inspection or repair of such apparatus or redirect power or other reasons. When a switch is called on to close and the break jaw and/or blade is covered with a build-up of ice, the blade must be closed rapidly to impart a chopping action to break through the ice. In the case where the switch has no ice shield or is mounted in an orientation where an ice shield cannot be used to keep the switch contacts free of ice, the conventional folding blade will often malfunction by prematurely straightening, since the joint spring has limited force to keep the blade folded, often resulting in misalignment, for example, of a break jaw contact pin on the blade tip with a notch within the switch jaw contacts. This situation requires opening and refolding the switch blade using a hot stick and attempting to close the switch again, possibly repeatedly.
It is therefore an object of the present invention to provide a high voltage folding disconnect switch, such as a side break electric disconnect switch, with a simple reliable apparatus for preventing premature straightening of the blade during closing; to aid the switch in breaking ice build-up on the switch blade and break jaw contacts during switch opening or closing; and, to cause proper alignment of the folding switch blade with the break jaw contact during closing, for example, by proper alignment of the break jaw contact pin on the blade tip with the notch within the switch jaw contacts.